The present invention relates to equipment for winding webs of sheet material such as paper, plastic, metal foil, etc., as well as to the method for winding such webs, and relates more particularly to equipment for re-winding big rolls of paper into smaller rolls, which equipment is known in the paper industry as a high speed automatic rewinder.
In the production of toilet tissue, absorbent kitchen towels and other sanitary paper products sold in roll form, it is customary to manufacture the webs of paper in large "parent" rolls on massive paper-making machines. These "parent" rolls may be as large as five feet in diameter and ten to twelve feet in length and, because the paper is extremely thin and light-weight, may contain several miles of paper web.
In order to produce a commercially saleable and easily marketable product, these large "parent" rolls must be rewound into smaller household-size rolls of the type commonly found in kitchens, bathrooms and public toilets around the world. The machine to produce these smaller rolls is called a "re-winder" and although it is under the control of a machine operator, it is generally known as an automatic re-winder because the machine runs continuously, producing from one "parent" roll hundreds of "logs"of small diameter (approximately 4-5 inches) on a cardboard tube or core 10 to 12 feet in length. The web is also perforated into sheet-size sections. All this is done under the pre-controlled settings of the machine once the "parent" roll of paper is installed in the re-winder and the machine is started. Hence the use of the phrase "automatic re-winder". The "logs" are automatically removed from the re-winder and subsequently cut into individual smaller rolls.
It is important in the economy of this industry that such automatic re-winders operate at high speed and produce finished logs of uniform diameter, accurate sheet-count and sheet-length, while at the same time insuring the quality of the product with regard to appearance and also for subsequent handling in packaging machines.
From the foregoing it is evident that of primary importance in this field of endeavour is the provision of effective high-speed equipment which can produce the roll products accurately and efficiently. However, it is equally important that the equipment and the processes be relatively inexpensive and economical to operate.
Although the prior art is replete with disclosures of high speed automatic re-winders, not all of them have been dependable or economical. The present invention provides an apparatus and method for re-winding webs automatically under conditions heretofore not achievable by the prior art devices.
Of particular importance is the provision of devices to provide a "cut-off" of web under controlled conditions so that an absolutely accurate sheet count (or sheet length) is achieved. It is also important that the leading edge of the severed web be transferred to a newly-positioned core rapidly and repeatedly. Further, the diameter of the finished roll or log must be carefully and accurately controlled (despite variations in bulk, caliper, softness, extensibility etc. of the paper).
The prior art of some importance in this field, over which the present invention is an improvement, includes not only my own British Pat. No. 1,435,525 French Pat. No. 2,193,387, German Pat. No. 2,335,930 and Italian Pat. No. 963,047 but also U.S. Pat. Nos. Re. 28,353, 3,247,746, 3,264,921 and 3,179,348 (the latter of which are assigned to the Paper Converting Machine Company of Green Bay, Wis.), 3,540,671 (which is the property of Jagenberg of Germany), 3,148,843 (which is the property of the Hudson-Sharp division of Food Machinery Corp.) and 3,123,315 (which is the property of Dietz Machine Comapny).